Extracoporeal ultrasonic lithotripter with a variable focus

ABSTRACT

A therapeutical apparatus includes a measuring apparatus including a probe which generates an X-ray or ultrasonic wave in order to detect the location of a target to be treated such as calculi situated within the kidney, liver, biliary ducts. A therapeutical energy generator generates a shock wave of sufficient energy for purposes of therapy externally of the physical body and focuses it upon the target. Structure is provided for causing a displacement of the generator and the measuring apparatus around the surface of a patient. Structure is provided to activate the generator.

This application is a division of Ser. No. 182,785, filed on Apr. 18,1988, now U.S. Pat. No. 4,984,575.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a therapeutical apparatus ofextracorporeal type, and more particularly, to a therapeutical apparatusof extracorporeal type in which an object to be treated (such as acalculus formed within a physical body of a patient) is detected by ameasuring apparatus, and therapeutic shock wave energy which isgenerated externally of the physical body is focussed upon the object tofracture it, and specifically, to an ultrasonic therapeutical apparatuswhich focuses an ultrasonic shock wave from a source located externallyof the physical body upon the object to be treated for the purpose offracturing the same.

2. Prior Art

An arrangement which utilizes an X-ray or ultrasonic measuring apparatusto detect the presence of a calculus formed in a bile duct or kidney,and which also utilizes therapeutical energy in the form of a shock wavewhich is produced, as by voltage discharge or ultrasonic vibration,externally of the physical body of a patient and is focussed upon thecalculus to fracture it, is disclosed in U.S. Pat. No. 4,617,931. Asdisclosed in this patent, a probe with piezoelectric elements disposedin an array in a mosaic pattern along a quadratic surface is broughtinto contact with a patient's back via a water bag filled with anultrasonic wave transmitting medium such as water interposedtherebetween to focus an ultrasonic shock wave from the piezoelectricelements upon a calculus, as formed within a kidney, to fracture it. Asdisclosed in Japanese Laid-Open Patent Applications No. 31,140/1988 andNo. 45,747/1986, an ultrasonic probe may move across an extensive areaand focus an ultrasonic wave of increased intensity upon a calculus onceit is located. Japanese Laid-Open Patent Application No. 37,149/1986discloses a measuring apparatus including a detection system whichdetermines positions in two directions. The present applicant has alsoproposed an arrangement which permits displacement of the ultrasonicprobe in a direction perpendicular to the scan direction, as disclosedin Japanese Patent Application No. 282,979/1986. U.S. Pat. No. 4,526,168discloses a technique for focussing an ultrasonic wave upon a calculusby changing the timing and phases with which a plurality ofpiezoelectric elements are driven. In the ultrasonic therapeuticalapparatus disclosed in U.S. Pat. No. 4,617,931, the ultrasonic probe islocated only at the center of an ultrasonic wave generator whichprovides an ultrasonic wave of an increased intensity, resulting in alimited scanning field over which an observation is possible. However,such an arrangement may fail to locate a calculus. When displacement ofthe probe in a direction perpendicular to the scan direction is enabledas disclosed in Japanese Patent Application No. 282,979/1986, trackingthe movement of the calculus is possible, but it is still difficult tolocate the calculus before the therapy is conducted. A manual focussingoperation results in a low hit rate of the ultrasonic wave whenever thecalculus happens to move as a result of breathing.

The ultrasonic therapeutical apparatus disclosed in Japanese Laid-OpenPatent Application No. 31,140/1986 enables the extent of observation tobe increased, but involves a combination with a patient suspensionsystem with the patient suspended in a bath in a water vessel, thusdisadvantageously requiring a very bulky arrangement. The ultrasonictherapeutical apparatus disclosed in Japanese Laid-Open PatentApplication No. 37,149/1986 uses X-ray in its detector, which may behazardous to the patient. In addition, where a pair of ultrasonic probesare employed, they are located such that each scan plane passes throughthe focus of a reflector of the shock wave and such that their axes areperpendicular to each other. This limits the extent of observation whichis available, and thus still leaves much to be improved.

The apparatus disclosed in U.S. Pat. No. 4,617,931 includes means forfocussing a shock wave on a calculus. Specifically, an ultrasonic waveor X-ray is employed to detect the spatial location of a calculus withinthe physical body of a patient, as illustrated in FIG. 46, where thefocal point of the shock wave is indicated by a marker on an image 300which is obtained by ultrasonic or X-ray tomography. The positioning isachieved by bringing an image 302 of a calculus into alignment with themarker. Thus, the position of a focus F is indicated as shown at 304 ona display 303, and the means for generating a shock wave is moved sothat the image 302 of the calculus is aligned with the position of thefocus F. However, such technique only indicates the focal point of thedisplay.

Accordingly, where organs such as lungs, intestines or bones, which aresensitive to the shock wave, are located around the calculus when thelatter is to be fractured, there arises a significant problem inasmuchas such organ may be damaged or otherwise adversely influenced by theshock wave.

Another form of therapeutical apparatus of extracorporeal type isdisclosed in Japanese Patent Application No. 282,980/1986 (see FIGS. 44and 45). The apparatus includes ultrasonic measuring means 311 (locationdetecting means) which detects the location of a calculus within thephysical body, positioning signal generating means 312, focus shiftingmeans 313 and shock wave generating means 314 which generates a shockwave used to fracture a calculus.

The ultrasonic measuring means 311 includes an ultrasonic measuring unit317 which radiates an ultrasonic wave toward a patient 315 to detect thelocation of a calculus 316, and a display unit 318 which receives adetection signal to indicate the location of the calculus on a CRTscreen.

The positioning signal generating means 312 includes a single generator320 which fixes a marker on a given point on the screen of the displayunit 318 and produces a signal which is delivered to focus shiftingmeans 313 which is effective to bring the focus of the fracturing shockwave into alignment with the marker. The generator 320 is effective toprocess the image of the detected calculus so that an operator (such asa surgeon) can recognize the size or the number of calculus or calculidisplayed and to indicate a most effective signal on the screen as by alight pen to indicate the sequence in which the calculi are to befractured in order of decreasing size, or to indicate a particularregion of a coral calculus where the fracture is to be initiated or tochange the focal point of the shock wave in response to the location andsize of the calculus which is performed periodically during thefracturing process because of a displacement of the calculus. Thegenerator stores such signals, and delivers them to a drive unit 319which shifts the shock wave generator during the fracturing process.

The focus shifting means 319 or the drive unit which shifts the shockwave generator operates to drive both a water bag 321 and a shock wavegenerator 322 by means of a numerically controlled robot in accordancewith the positioning signal. The shock wave generator 322 includes aplurality of ultrasonic vibrators or piezoelectric elements 323 whichare applied to and secured to the front surface of a mounting plate 324,which is formed as a spherical surface, in a mosaic pattern. The frontsurface of the piezoelectric elements which emit the shock wave isdirected toward the patient 315. The water bag 321 includes anultrasonic wave transmitting medium and means for injecting liquidmedium and controlling the pressure of the medium.

The water bag is interposed between the shock wave generator 322 and thepatient 315. The shock wave transmitting liquid (such as water) fillsthe bag 321.

The shock wave generating means 314 includes a known ultrasonic pulsevoltage generator for driving the piezoelectric elements 323.

FIG. 45 indicates the sequence of operation performed by the apparatusmentioned above. Initially, the location of the calculus within thephysical body of a patient is determined by the measuring means 311. Thepositioning signal generating means 312 analyses the condition of thecalculus which is detected by the measuring means. An operator (such asa surgeon) selects an optimum procedure to treat the calculus dependingon the kind thereof. In response thereto, a positioning signal (whichdetermines the sequence of treatment) is stored. The focus shiftingmeans 313 is activated in accordance with the positioning signal todrive the water bag 321 and the shock wave generator 322 so that theshock wave is focussed upon the calculus. Subsequently, a shock wave isgenerated in response to the shock wave generating means 314 to fracturethe calculus. After a given number of shock waves have been generated,the procedure is temporarily stopped, and the size of the remainingcalculus or the focal point of the shock wave is determined again, andthe above operation is repeated until the calculus is completelyfractured.

However, in the therapeutical apparatus of extracorporeal type asmentioned above, the use of the ultrasonic wave for observing thelocation of a calculus and for aiming fails to provide a tomographicimage of good quality because of the spacing between the apparatus andthe patient. This makes it difficult to aim the apparatus.

In addition, in the apparatus described above, the entire shock wavegenerator has been moved in order to bring the focal point of the shockwave into alignment with the calculus. However, because the shock wavegenerator (including the water bag) is of an increased weight, anextensive unit is required for such movement and the apparatus lacksspeed.

On the other hand, a calculus or tumor which is to be treated by such anapparatus tends to move in response to breathing or movement of bloodvessel, and thus may be displaced from the focal point of the ultrasonicbeam. In such instance, the focal point of the ultrasonic beam must bealigned with a region to be treated to avoid wasteful generation of anultrasonic wave. This increases the length of time required for thetherapy and also jeopardizes normal tissues. Movement caused bybreathing may be rapid enough to prevent automatic tracking of the focalpoint of the ultrasonic beam on the moving calculus since the water bagitself has a given magnitude.

Almost all apparatus of the kind described utilize a devoted bed onwhich a patient is positioned in a supine posture. The bed includes atable section supporting an upper region of a patient including hisshoulder and head and another table section supporting a lower sectionextending from the waist to the feet, leaving a free space between thebreast and the abdomen. A patient is laid in a supine posture on thebed, and the measuring apparatus as well as a unit for generatingtherapeutical energy are brought close to or into abutment against thepatient to perform the treatment. Accordingly, the patient has a smalldegree of freedom during the therapy, which restricts the spacerequirement for the measuring apparatus and the energy generatingapparatus. Specifically, with an X-ray measuring apparatus, it is onlypossible to cause the X-ray to transmit through the physical body of apatient. With an ultrasonic measuring apparatus, it is only possible tomove the ultrasonic vibrator along the surface of the physical body.

There has been no capability to provide an efficient, fine adjustment ofthe angle with which the X-ray transmits or the angle at which theultrasonic wave is emitted. It has been impossible to locate a shockwave generator at an angle which avoids the lung when treating a biliarycalculus or to adjust the angle at which the shock wave is emitted to anefficient angle. It has only been possible to guide the shock wavegenerator along the physical body of a patient.

Usually, a supine posture is chosen for therapy of a biliary calculuswhile either a supine or prone posture is chosen for treating a renalcalculus, and it is unfavorable that a posture used for the therapy berestricted by a devoted bed.

Hospitals usually have an X-ray apparatus and an ultrasonic diagnosticapparatus, and therefore it is uneconomical for the hospital to purchasea separate extracorporeal therapeutical apparatus with a devoted bed. Itis desirable that a therapeutical apparatus of extracorporeal type beprovided which uses a common bed which allows a free choice of eithersupine or prone posture.

Thus, an ordinary hospital is usually provided with an X-ray unit orultrasonic diagnostic apparatus which may be used as the measuringapparatus mentioned above as well as associated patient beds. If anextracorporeal therapeutical apparatus as mentioned above must beprovided anew, an increased demand in space requirement and additionalcost result.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a therapeuticalapparatus of extracorporeal type which permits a choice of therapypostures and which improves economy and which is capable of adjusting anangle with which a measuring apparatus makes an observation as well asan angle with which energy from a therapeutical energy generator isemitted or directed.

It is a second object of the invention to provide a therapeuticalapparatus of extracorporeal type which requires less space and reducescost while utilizing an ultrasonic diagnostic apparatus or X-ray unitwhich is already available in the hospital.

It is a third object of the invention to eliminate disadvantages of theprior art, by providing an ultrasonic therapeutical apparatus havingenhanced measurement capabilities while facilitating the location of acalculus before therapy and also enabling an accurate tracking of thecalculus for efficient therapy.

It is a fourth object of the invention to provide a therapeuticalapparatus of extracorporeal type which is capable of detecting movementof a calculus to bring a focus into alignment with the calculus whichhas quickly moved, thus providing efficient and dependable therapy.

It is a fifth object of the invention to provide a therapeuticalapparatus of extracorporeal type which is capable of reliably bringingthe focal point of a shock wave into alignment with a recognizedcalculus in an accurate manner while avoiding adverse influence uponother organs, thus further improving the fracture efficiency andreducing the length of time required for the therapy while avoiding anypains to the patient.

It is a sixth object of the invention to provide an ultrasonic probehaving a simplified construction and exhibiting an increased efficiency.In accordance with the invention, the patient may assume any postureduring therapy. The angle at which an observation is made as well as theangle at which the shock wave used for the therapy is emitted can beaccurately adjusted to achieve a most efficient operation. The apparatusof the invention may be efficiently used in combination with any otherinstrument such as an X-ray unit. This avoids unnecessary expenses andreduces space requirements while improving the degree of freedom andeconomy.

In accordance with the invention, an ultrasonic shock wave is radiatedin recognition of the location within a specified area (an area ofinterest-AOI) where a calculus exists, thus eliminating a wastefulemission of an ultrasonic shock wave to provide a further enhancedtherapy efficiency.

In accordance with the invention, an ultrasonic probe allows anincreased coverage for observation, facilitating the location of acalculus before it is treated. In this manner, any resort to a separateultrasonic observation unit as has been done conventionally is avoided.The locating and the automatic tracking of a calculus enable the lengthof time required for the therapy to be reduced and any pain caused tothe patient to be diminished, because an efficient treatment isachieved.

In accordance with the invention, the focal point of an ultrasonic shockwave may be brought into alignment with any object being treated whichmay move rapidly as a result of breathing, by merely choosing ultrasonicvibrators which are to be driven while maintaining a shock wavegenerator at a fixed position. The focal point is brought into alignmentwith the object by an electronic technique which utilizes a CPU to drivea drive circuit, and hence the arrangement is compact in constructionand efficient in achieving the therapy of an object such as a calculus.

Additionally, if a calculus or tumor changes its position because of thepatient's breathing, the ultrasonic wave may be maintained focussed onthe object being treated. This improves the efficiency of the therapyand enhances the safety of the therapy by avoiding concentration of anultrasonic wave upon areas which are unrelated to treatment. This isachieved by feeding a digital signal representing the location of acalculus or tumor detected by the ultrasonic probe to a CPU, which thenautomatically focuses the ultrasonic wave on an area to be treated, thusavoiding manual intervention and allowing an automatic tracking.

Additionally, in accordance with the invention, an image representing aspatial location of a focus within the patient may be obtained bydriving ultrasonic vibrators. Data representing the distribution of theintensity of the ultrasonic wave which is previously calculated issuperimposed upon the image to provide a color display, whereby thelocation of the calculus may be readily and reliably positioned to apoint where the intensity of the shock wave is at its maximum. This alsoallows a decision to see if any organ such as a lung, intestine or boneswhich are sensitive to the shock wave is located within a region wherethe intensity of the shock wave is significant. In this manner, anydamage to such organ may be avoided by changing the posture of thepatient or by moving the shock wave generator.

Other features and advantages of the present invention will becomeapparent from the following description of the invention, with referenceto the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation of an apparatus according to a firstembodiment of the invention;

FIGS. 2 and 3 are a fragmentary rear view and a side elevation,illustrating manners of operating the apparatus illustrated in FIG. 1;

FIG. 4 is a schematic view of a therapeutical apparatus according to asecond embodiment of the invention;

FIG. 5 is a side elevation of another form of guide arm;

FIG. 6 is a side elevation of an apparatus according to the invention incombination with an X-ray unit;

FIG. 7 is a side elevation of another form of the therapeuticalapparatus;

FIG. 8 is a perspective view of an apparatus according to a thirdembodiment of the invention;

FIG. 9 is a fragmentary, enlarged, longitudinal section illustrating onemanner of use of the apparatus illustrated in FIG. 8;

FIG. 10 is a longitudinal section of a water bag in its shrunkcondition;

FIG. 11 is a schematic view, partly in longitudinal section, of anapparatus according to a fourth embodiment of the invention;

FIG. 12 is a perspective view of an apparatus according to a fifthembodiment of the invention;

FIG. 13 is an enlarged, fragmentary cross sectional view of theapparatus illustrated in FIG. 12;

FIG. 14 is a block diagram of an apparatus according to a sixthembodiment of the invention;

FIG. 15 is an illustration of a monitor screen of a display unitillustrated in FIG. 14;

FIG. 16 is a flowchart illustrating the operation of an apparatusaccording to the invention;

FIG. 17 is a flowchart illustrating the operation of an apparatusaccording to a seventh embodiment of the invention;

FIG. 18 is a block diagram of an apparatus according to an eighthembodiment of the invention;

FIG. 19 is a fragmentary cross sectional view of an apparatus accordingto a ninth embodiment of the invention;

FIG. 20 is a schematic illustration of an apparatus according to a tenthembodiment of the invention;

FIG. 21 is a block diagram of an apparatus according to an eleventhembodiment of the invention;

FIG. 22 is a diagram illustrating the relationship between the wavesurface and the focal point in the arrangement illustrated in FIG. 21;

FIG. 23 graphically illustrates the waveforms of ultrasonic signals fromindividual piezoelectric elements used in the arrangement of FIG. 21;

FIG. 24 is a flowchart of the operation of the arrangement illustratedin FIG. 21;

FIG. 25 is a perspective view of an apparatus according to a twelfthembodiment of the invention;

FIGS. 26A, B and C illustrate an apparatus according to a thirteenthembodiment of the invention; FIG. 26A being a cross sectional view ofthe relationship between an acoustical prism and a focal point; FIG. 26Bbeing a perspective view of an acoustical prism; and FIG. 26C being anenlarged, fragmentary cross sectional view of an acoustical prism;

FIG. 27 is a schematic illustration of an apparatus according to afourteenth embodiment of the invention;

FIG. 28 is a schematic illustration of an apparatus according to afifteenth embodiment of the invention;

FIG. 29 is a diagram illustrating an echo-through which may occur in atomographic image formed by an ultrasonic probe;

FIG. 30 is a schematic illustration of an apparatus according to asixteenth embodiment of the invention;

FIG. 31 is a diagram of an example of angle of rotation of an ultrasonicprobe used in the apparatus of FIG. 30;

FIG. 32 illustrates several B-mode images at different angles ofrotation of the probe;

FIG. 33 is a flowchart illustrating a procedure which is utilized in thesixteenth embodiment to bring a calculus into the focal point of anarray of vibrators;

FIG. 34 illustrates a B-mode image, specifically illustrating therelationship between a calculus and the focal point of an array ofultrasonic vibrators on a P2 image plane illustrated in FIG. 32;

FIG. 35 shows a B-mode image, illustrating another use of the apparatusillustrated in FIG. 30;

FIG. 36 is a block diagram of display means used in an apparatusaccording to a seventeenth embodiment of the invention;

FIG. 37 is a diagram illustrating a data screen of the display;

FIG. 38 is a block diagram of another form of display means;

FIG. 39 is a longitudinal section through an ultrasonic probe and ashock wave generator which are used in an apparatus according to aneighteenth embodiment of the invention;

FIG. 40 is a plan view of the probe illustrated in FIG. 39;

FIG. 41 is an enlarged, fragmentary longitudinal section of the probeillustrated in FIG. 39;

FIGS. 42 and 43 are a perspective view and a plan view of another formof probe;

FIG. 44 is a schematic illustration of a conventional apparatus;

FIG. 45 is a block diagram illustrating the sequence of operation of theapparatus illustrated in FIG. 44; and

FIG. 46 is a diagram illustrating a conventional data display screen.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, the invention will now be described withreference to several embodiments thereof. In the description to follow,a therapeutical apparatus of extracorporeal type is constructed as acalculus fracture apparatus, but it should be understood that theinvention is not limited in its application to the fracture of acalculus.

The apparatus 1 of FIG. 1 includes a movable body 2 on which anoperating keyboard 3 and a monitor display 4 are installed. An operatinghead 7 is also carried. The head 7 guides a measuring apparatus 5 and atherapeutical energy generator 6 to a desired angular position.

The head 7 is mounted on the top end of a rotatable shaft 8 which isvertically supported within the body 2. The shaft 8 can be elevated upand down to permit vertical movement of the head 7, which is alsomovable toward and away from a patient 11 by a mechanism, not shown. Thehead 7 carries a support shaft 9 which projects horizontally andforwardly, with a guide arm 10 mounted on the free end of the supportshaft 9. The measuring apparatus 5 is slidably mounted on the arm 10 bya movable mount 5a, and the energy generator 6 is also slidably mountedon the arm 10 by a movable mount 6a. The guide arm 10 is arcuate orsemicircular in the present embodiment so that both the measuringapparatus 5 and the generator 6 may be moved around one-half thecircumference of the patient 11. The support shaft 9 is also rotatablearound its axis, whereby the guide arm 10 is rotatable through 360°around an extension of the axis of the support shaft 9.

The measuring apparatus 5 (mounted on the movable mount 5a) includes anultrasonic vibrator which performs a sector scan, for example, radiatingan ultrasonic wave toward the patient 11 to detect the location of acalculus 13 which may be located within a kidney 12 of the patient. Thedetected renal calculus 13 is displayed on the screen of the monitordisplay 4 (which may include a cathode ray tube).

The therapeutical energy generator 6 (mounted on the movable mount 6a)includes a high tension discharge type source for generating shock waveenergy. The source is focussed upon the renal calculus 13 within thepatient 11, through an interposed water bag 14 (such as GOATEX(trademark)) which is filled with a shock wave transmitting medium (suchas water) for fracturing the calculus 13.

In operation, the patient 11 usually lies on an ordinary bed 15 in proneposture, and the body 2 is moved close to the patient. By adjusting theoperating head 7 back and forth and up and down, the guide arm 10 isbrought in spaced, opposing relationship with the circumference of thepatient 11 to facilitate detection and fracture of the calculus bybringing the measuring apparatus 5 and the energy generator 6 close toor in abutment against the surface of the patient. As illustrated inFIG. 2, the support shaft 9 may be rotated around its axis to bring theguide arm 10 to an inclined position with respect to the surface of thepatient so that the generator 6 may be brought to an angular position tomaximize fracture efficiency or where the location of a lung or the likemay be avoided from the path of the shock wave energy.

Where the patient 11 lies on the bed 15 in supine posture as illustratedin FIG. 2, the support shaft 9 may be rotated through 180° to positionthe guide arm 10 in the space below the bed 15, whereby the measuringapparatus 5 and the generator 6 are brought close to or into abutmentagainst the patient 11 from the underside thereof for therapy.

FIG. 4 is a schematic illustration of an apparatus according to a secondembodiment of the invention. This apparatus differs from the firstembodiment in that the energy generator 6 includes an ultrasonic shockwave generator 16. Specifically, the generator 16 includes a mountingplate 17 in the form of a spherical shell. A multiplicity of ultrasonicvibrators 18, formed by piezoelectric elements, are secured in a mosaicpattern on the internal surface of the shell so that the front surfaceof each element (on which a shock wave is generated) faces the patient11. A water bag 19 of a material such as GOATEX (trademark) whichincludes liquid injection means and pressure control means is interposedbetween the generator and the patient 11. The bag 19 is filled with ashock wave transmitting liquid such as water. An ultrasonic measuringapparatus 20 which is adapted for a linear scan or a sector scan ismounted centrally on the mounting plate 17.

The ultrasonic energy generator 16 is movably mounted on the guide arm10 by a movable mount 16a. In other respects, the arrangement is similarto the first embodiment, and this embodiment operates similarly and witha similar effect as in the first embodiment.

In FIG. 5, the guide arm 10 of the first embodiment is replaced by aC-ring shaped guide arm 21 on which the measuring apparatus 5 and thetherapeutical energy generator 6 may be movably mounted. Thisfacilitates changing the posture of the patient. This permitsutilization of an X-ray unit having a C-shaped guide arm as themeasuring apparatus associated with the therapeutical apparatus of theinvention.

Specifically, as illustrated in FIG. 6, an X-ray unit 25 carries aC-shaped guide arm 24 on which an X-ray emitter 22 and an imageintensifier 23 (which is an X-ray receptor and includesphotomultipliers) are mounted in opposing relationship. The unit 25 maybe disposed along one side of the patient 11 lying on the bed 15 whilethe therapeutical apparatus 1 (including either the therapeutical energygenerator 6 or 16) mounted on the guide arm 10 may be disposed on theother side. In this manner, the location of the calculus 13 may bedetected by the X-ray observation unit 25, and then the therapeuticalapparatus 1 may be activated to fracture the calculus 13.

The therapeutical apparatus of the invention may be used in combinationwith an endoscope. As illustrated in FIG. 7, the body 2 of thetherapeutical apparatus may be provided with shelves 26 on which a lightsource unit 27 for the endoscope and a treatment tool 28 may beconveniently located.

FIGS. 8 to 10 illustrate a third embodiment of the invention whichutilizes an X-ray unit (already provided in the hospital) as themeasuring apparatus. Specifically, the X-ray unit includes an X-rayemitter 32 on which a therapeutical energy generator 31 is detachablymounted. The emitter 32 is movable up and down above a surgical bed 33and has an arm-shaped mounting member 48 secured thereto at a downwardangle. The generator 31 is detachably mounted on the mounting member 48by mounting screws 49. The generator 31 is of a high tension dischargetype and includes an external housing 39 having a focussing reflector 40disposed in its free end. The reflector has an elliptical surface. Adischarge electrode 42 is located at one of the foci of the ellipticalsurface, and the opening of the reflector 40 is covered by a flexiblewater bag 41 which is filled with a shock wave transmitting medium 43such as water, thus filling the space between the external surface of apatient 50 and the discharge electrode 42. Piping 44, 45 inside of thehousing 39 supplies or discharges water to and from the bag 41. Theelectrode 42 is connected through a connection cord 46 passing throughthe housing 39 to a source of high tension 34, whereby a dischargevoltage may be applied to the electrode. An ultrasonic probe 47 (whichis used as an auxiliary measuring apparatus) is located along theunderside of the housing 39.

The X-ray emitter 32 is supported by a support member 36 to be movablevertically above the surgical bed 33. The bed is conventionallyhorizontally translatable in two dimensions. The X-ray is transmittedthrough the patient 50 lying on the bed to be received by an X-rayreceptor or an image intensifier 35 (including photomultipliers) locatedbelow the bed 33. The arrangement may include a monitor 37 whichindicates the focus of the shock wave and an X-ray monitor 38. Thepatient's kidney 50 is indicated at 51, with a calculus 52 locatedtherein.

In operation, when the energy generator 31 is mounted on the X-raymeasuring apparatus, the system is adjusted so that the axes ofultrasonic energy and X-ray radiation intersect each other at thecalculus 52, as indicated in FIG. 9. The apparatus is connected to thesource 34 and to a source of water, not shown, through the piping 44,45. The patient 50 then lies on the bed 33. The X-ray unit is thenoperated to cause the X-ray to pass through the kidney 51 to observe anddetect the calculus 52. At this time, the water bag 41 should be shrunkas indicated in FIG. 10 to approach the opening of the reflector 40, byremoving the water therefrom, to prevent the bag from interfering withthe X-ray unit. After the calculus 52 is detected, the water is suppliedto the water bag 41 to expand it, and the support member 36 is operatedto bring the bag into close contact with the patient. While observingthe monitor 37, the location of the calculus 52 is brought to the otherfocal point of the elliptical reflector 40. A high tension is thenapplied to the electrode 42 to cause its discharge, whereupon shock waveenergy is focussed upon the calculus 52 located within the kidney 51,thus fracturing it as intended to allow it to be digested in a naturalmanner.

While the apparatus may be used in combination with an X-ray unit todetect the location of a calculus, the location of a calculus may alsobe detected by an ultrasonic probe 47 mounted on a housing 39. Inaddition, the energy generator 31 may be detachably mounted on the imageintensifier 35 of the X-ray unit with a similar effect.

FIG. 11 is a longitudinal section through an apparatus according to afourth embodiment of the invention, which is similar to the apparatusillustrated in FIGS. 8 and 9. Accordingly, similar parts are designatedby corresponding numerals without repeating their description.Specifically, the only difference between the embodiments is that atherapeutical energy generator 31A is detachably mounted on the surgicalbed in distinction to the energy generator 31 which is detachablymounted on the X-ray emitter 32 or the image intensifier 35 in theembodiment of FIGS. 8 and 9. Thus, referring to FIG. 11, the generator31A is detachably mounted on a surgical bed 33A by mounting screws 49Awith a mounting member 48A interposed therebetween. When the energygenerator is directly mounted on the bed 33A, the generator 31A may bemore firmly secured to improve stability during use. The apparatusfunctions in a similar manner and achieves a similar effect as theapparatus illustrated in FIGS. 8 and 9.

FIG. 12 is a schematic illustration of an apparatus according to a fifthembodiment of the invention which is used in combination with anexisting ultrasonic diagnostic apparatus utilized as a measuringapparatus, with a therapeutical energy generator detachably mountedthereon. Specifically, FIG. 12 illustrates a therapeutical energygenerator 31B, an ultrasonic diagnostic observation apparatus 32A, anobservation monitor 53, an ultrasonic probe of mechanical scan typeassociated with the apparatus 32A, and an arm 55 which carries the probe54 in a movable manner. As illustrated, the ultrasonic diagnosticapparatus 32A is free to move above, and the probe 54 may be freelypositioned relative to an affected part 57 of a patient 56 (see FIG. 13)by means of the arm 56.

Referring to FIG. 13, the therapeutical energy generator 31B includes abody 58 in the form of a cup-shaped casing having an opening 59centrally in its top in which the probe 54 is fitted and having a bottomopening which is closed by a water bag 60. An array of piezoelectricelements 65 is disposed along a spherical surface on the internal uppersurface of the body 58. The water bag 60 is filled with water 61 actingas an ultrasonic wave transmitting medium, and an O-ring 62 is fittedaround the top opening 59 to maintain the body 58 watertight against theprobe 54. The top of the body 58 is integrally formed with threethreaded lugs 63, which are engaged by mounting screws 64 to permit theapparatus 31B to be detachably mounted on the probe 54 of the ultrasonicdiagnostic apparatus 32A. The piezoelectric elements 65 are connected toa drive unit 66, and shock wave energy generated by the piezoelectricelements 65 is focussed upon the affected part 57 (such as the calculusof the patient 56) for fracturing it.

In use, the therapeutical energy generator 31B is mounted on the probe54 of the ultrasonic diagnostic apparatus 32A by the mounting screws 64,and the piezoelectric elements are connected to the drive unit 66. Thegenerator 31B is located relative to the affected part 57 of the patient56 with the surface of the water bag 60 in close contact therewith asillustrated in FIG. 13. The probe 54 detects the affected part, such asa calculus, and then the affected part 57 is brought to the focal pointof the array of piezoelectric elements 65. A drive voltage is thenapplied to the piezoelectric elements 65 from the drive unit 66 togenerate a shock wave, which is focussed upon the affected part 57 tofracture it. In this manner, the apparatus of the present embodimentoperates similarly and achieves a similar effect as the apparatus of thethird and the fourth embodiments.

FIG. 14 illustrates an apparatus according to a sixth embodiment of theinvention which is designed for use when a calculus is susceptible tomotion (as by breathing) at the instant when the calculus is targeted.

Specifically, a monitor display 73 is fed with a calculus locationsignal from a digital scan converter 82 for displaying an image of thecalculus. A calculus 71 within a patient 80 is detected by an ultrasonicdetector 83, which feeds a signal to the converter 82 through an analogvariable delay and adder 84 and a receiver 85. A digital variable delaypulse generator 87 is then synchronized with the converter 82 through asynchronization control circuit 86, and controls a high frequency pulsegenerator 88, which feeds the ultrasonic detector 83. The detector 83includes a planar array of elements, and hence the delay pulse generator87 is used to delay pulses for the purpose of focussing.

A positioning signal (such as from a light pen 90) is fed through I/Oport 89 to be stored in a control memory 100 (which includes CPU 91, RAM92 and ROM 93) so as to be delivered to the display 73 at suitabletimes. A shock wave start switch 94 and a number of shock wavespresetting circuit 95 are connected to the memory through I/O port 96,and a shock wave generator drive circuit 97 is connected to a data busthrough an I/O port 98.

Operation of the apparatus illustrated in FIG. 14 will be describedbelow with reference to FIGS. 15 and 16. The location of the calculus 71is detected by a measuring apparatus, not shown, and its image isdisplayed to allow a recognition of the number of calculi, its or theirsize, configuration and location. Such information is displayed on themonitor screen of the display 73 in a designated area. A region 68subject to determination by an ultrasonic observation apparatus isindicated on the monitor screen of the display 73, as indicated in FIG.15. Observing calculus information displayed on the monitor screen, anoperator (such as a physician) specifies a designated area 69 (an areaof interest-AOI) by the light pen 90. This information is fed to andstored in the control memory 100 through the I/O port 89.

When the shock wave start switch 94 of FIG. 14 is turned on to fracturethe calculus, the ultrasonic fracturing operation is initiated at thepoint in time when the designated area 69 stored in the control memory100 coincides with the specified location of the calculus 71 (which isdetermined by the ultrasonic measuring apparatus). Thus, CPU 91 triggersthe shock wave generator drive circuit 97 a predetermined number oftimes (preset in the circuit 98), through the data bus and I/O port 98.Each time the drive circuit 97 is triggered, the ultrasonic shock waveis emitted and directed to the calculus 71 at the specified locationwithin the coeloma. If the calculus 71 goes outside the specified areaduring the fracturing operation or when the calculus 71 is out of thespecified area from the beginning, CPU 91 does not deliver a triggerpulse if the start switch 94 is turned on. The calculus 71 to be treatedcan be recognized by a portion of ultrasonic data from the digital scanconverter 82 which is above a threshold value and which is locatedwithin an area specified by the operator on the monitor screen of thedisplay 33 by the light pen 90. Accordingly, if the calculus moves outof the specified area due to a breathing operation, the ultrasonic shockwave generator is turned off, thus avoiding a wasteful shock waveemission.

FIG. 17 is a flowchart for a seventh embodiment of the invention.Considering a renal calculus by way of example, movement of the calculus71 due to breathing has a regular periodicity. Accordingly, when thecalculus 71 is observed by the ultrasonic measuring apparatus for agiven time interval, the probable location of the calculus 71 can bedetermined. Thus, by adding data stored in a frame memory (RAM 92)together over a given time interval, data representing a location wherethe calculus 71 exists for a longer time provides a greater sum, and ismore intensely displayed on the display 73. In this manner, adistribution of the probability of the location where the calculus 71exists is obtained. The location where the probability of the existenceof the calculus 71 is high is then recognized, and the specified area 69is specified on the monitor screen of the display 73 by the light pen90.

The ultrasonic shock wave is irradiated upon coincidence between thelocation of the calculus 71 (determined by the ultrasonic measuringapparatus) and the specified area 69, but the shock wave generatorcannot be turned on in the absence of such coincidence. In this manner,the shock wave generator is turned on only when the calculus is wherethe probability of existence of the calculus 71 is at its maximum.

The target to be treated is not limited to the calculus 71 alone, nor isthe invention limited to a calculus fracturing apparatus. The inventionis equally applicable to any therapeutical apparatus in which it isdesired to focus an ultrasonic wave upon a target.

FIG. 18 illustrates an apparatus according to an eighth embodiment ofthe invention which enables the focal point of the ultrasonic shock waveto be shifted simply and rapidly. A body 101 includes a kidney 102 inwhich a calculus 103, the target to be treated, is located. To fracturethe calculus 103, a shock wave generator 107 (including an array ofultrasonic vibrators 105a to 105z disposed along a spherical surface ina mosaic pattern) contacts the body 101 with a water-filled bag 104interposed therebetween. A number of vibrators 105a to 105z (greaterthan the number illustrated in FIG. 18) may be employed.

Each of the ultrasonic vibrators 105a to 105z is connected to one of thedrive circuits 106a to 106z, each of which applies a drive voltage toits associated vibrator to cause the latter to generate an ultrasonicshock wave. An ultrasonic probe 110 (of mechanical scan type) is locatedat the center of the vibrators 105a to 105z. The probe 110 is connectedto an ultrasonic measuring apparatus 111, which feeds its output to CRTmonitor 112, and an A/D converter 113. An output from the converter 113is written into a frame memory 114. The frame memory 114 includes amemory area which corresponds to the screen of the monitor 112. Dataread out of the memory 114 is fed through readout buffer circuit 115 toa comparator 116. A multiplexer 119 (which switches between outputs of awrite address generator 117 and a read address generator 118) isconnected to the memory 114. An output from the comparator 116 and anoutput from the read address generator 118 are fed through a data bus120 to CPU 121.

An address bus 122 is connected to CPU 121, and both the address bus 122and the data bus 120 are connected to the drive circuits 106a to 106z.Peripheral circuits associated with CPU 121 such as memories, clockcircuits and a power supply for the drive circuits 106a to 106z areomitted from the illustration.

In operation, the ultrasonic probe 110 performs a sector scan with itsultrasonic wave output to derive an echo signal from the living body101, kidney 102m and calculus 103 with the shock wave generator 107 incontact with the body 101 and with the bag 104 interposed therebetween.The echo signal is processed in the ultrasonic measuring apparatus 111to derive a signal which represents a tomographic image of an objectbeing examined, and the tomographic image signal is displayed on CRTmonitor 112. The tomographic image signal output from the apparatus 111is fed to the converter 113, and each picture element signal is writteninto the frame memory 114. At this time, the multiplexer 119 selects anoutput from the write address generator 117, thus supplying a series ofwrite addresses to the memory 114.

When data representing one frame of tomographic image has been writteninto the memory 114, the multiplexer 119 switches to select an outputfrom the read address generator 118, thus reading data from the memoryand supplying it to the comparator 116 through the buffer 115. Thecomparator 116 determines that a particular picture element in the framerepresents the surface of the body 101 when its corresponding signalexceeds a threshold value. In response to addresses of those pictureelements which represent the surface of the body 101 and supplied to CPU121 through the data bus 120, CPU 121 operates to determine the distancefrom the surface of the body 101 to the location of the calculus 103within the kidney 102. It then calculates the distance from the shockwave generator 107 to the focal point of the ultrasonic shock wave. CPU121 then activates selected ultrasonic vibrators for emission of anultrasonic shock wave, depending on the distance calculated. Forexample, for a near distance, the vibrators 105a to 105q are selected,and for a medium distance, the vibrators 105f to 105u are selected. Theselection of particular ultrasonic vibrators is equivalent to choosingan aperture radius of the shock wave generator 107. Changing theaperture radius of the shock wave generator 107 changes the focal pointof the ultrasonic shock wave, thus allowing the focal point of theultrasonic shock wave to be coincident with the calculus 103. Thisaspect will be dealt with in more detail.

The acoustical field of a circular concave-surface vibrator is verycomplex. However, Rayleigh's formula describes sound pressure on acentral axis relative to mean sound pressure on a radiating surface asfollows: ##EQU1##

Where R represents the radius of curvature, λ the wavelength in amedium, a the radius of a vibrator and Z the distance to the focalpoint. While the formula appears to be complicated in nature, it may beassumed that R, λ and P_(A) are constants, thus reducing the formula toa relationship between a and z. Thus, assuming that the radius ofcurvature, the drive frequency and the sound pressure are constant, thedistance z to the focal point of the ultrasonic shock wave may bechanged by changing the radius of the vibrator. By way of example, whena drive frequency of 300 kHz and a radius of curvature of 100 mm areused, changing the radius of the vibrator in a range from 13 to 28 mmresults in changing the distance to the focal point from about 20 mm to115 mm. Thus, a number of ultrasonic vibrators to be driven may bechosen depending on the distance. If the calculus 103 is located nearerthe shock wave generator 107, a smaller aperture radius may be chosenfor the shock wave generator 107. Conversely, when the calculus 103 islocated further from the generator 107, a larger aperture radius may bechosen. In this manner, the focal point of the ultrasonic shock wave maybe brought into coincidence with the location of calculus 103. When areduced aperture radius is used, the number of driven vibratorsdecreases, thus decreasing the power available at the focal point of theshock wave. However, the voltage applied to each driven vibrator may beincreased, thus feeding greater power to each vibrator to achieve equalpower at the focal point, thus maintaining fracturing power at the samelevel. In this manner, the eighth embodiment permits the focal point ofa shock wave to be freely changed in the radial direction or in thedirection of depth by merely increasing or decreasing the number ofvibrators without an accompanying movement of the shock wave generator107.

If the calculus 103 moves in response to breathing, the ultrasonicmeasuring apparatus 111 is able to index such location as mentionedpreviously, and hence CPU 121 can choose a particular group ofultrasonic vibrators which are to be driven, thus maintaining the focalpoint of the shock wave coincident with the location of the calculus.This embodiment is also applicable to any arrangement in which anultrasonic wave must be focussed upon a target to be treated.

FIG. 19 shows an essential part of a ninth embodiment of the invention.When a particular group of ultrasonic vibrators, 105a to 105i, forexample, are centered about an ultrasonic vibrator 105e, the focal pointof the ultrasonic shock wave may be located at an upper focal point 103A(FIG. 19). Alternatively, when a group of ultrasonic vibrators 105j to105r centered about an ultrasonic vibrator 105n is chosen, the focalpoint of the shock waves shifts to a lower focal point 103B (FIG. 19).In this manner, an equal number of ultrasonic vibrators located oneither side of a particular ultrasonic vibrator may be freely driven toshift the focal point of the ultrasonic shock wave generator 107 in thesame direction as the shock wave generator 107. The general arrangement(including ultrasonic measuring apparatus and data bus) remains the sameas in the eighth embodiment, and hence is omitted from illustration.

FIG. 20 illustrates a tenth embodiment of the invention. Specifically, ashock wave generator 107A including a water bag 104A filled with wateris connected to a drive circuit 106A and carried by shift means 123. Thelocation of a calculus 103C within a living body 101A is recognized bythe combination of an ultrasonic probe 110A and ultrasonic measuringapparatus 124, and the shock wave generator 107A is moved through anincreased stroke by means of positioning signal generator 125 and theshift means 123 in order to bring the focus of the generator 107A intocoincidence with the calculus 103C. The focus of the generator 107A isonly temporarily brought into coincidence with the calculus 103C and thecalculus 103C continues to change its position due to breathing. Thismakes it difficult to maintain the focus of the generator 107A upon thecalculus 103C. Accordingly, ultrasonic vibrators 105A contained in thegenerator 107A are selectively driven in the same manner as describedabove in connection with the eighth and the ninth embodiment to shiftthe focal point of the ultrasonic shock wave, thereby bringing the focalpoint into alignment with the calculus 103C. In this manner, the focalpoint of the ultrasonic shock wave moves through an increased stroke bythe shift means 123 which carries the generator 107A, and is rapidlymoved through a reduced stroke by a selective energization of particulardriven ultrasonic vibrators.

FIG. 21 illustrates an apparatus according to an eleventh embodiment ofthe invention which is designed to concentrate the ultrasonic wave uponan affected area by controlling the timing of focussing of theultrasonic waves developed by the ultrasonic vibrators. Specifically, aliving body 101B includes a kidney 102B in which a calculus 103D to betreated is situated. In order to fracture the calculus 103D, a probewith piezoelectric elements 126a to 126l disposed along a quadraticsurface in a mosaic pattern is brought into contact with the living body101B with a water bag 104B filled with water interposed therebetween. Anumber of piezoelectric elements greater than those illustrated areactually used. The illustration is simplified for convenience.Piezoelectric elements 126a to 126l are connected to shock wavegenerating circuits 127a to 127l, respectively, which apply a pulsevoltage to the associated elements 126a to 126l to cause the latter toproduce a shock wave of an increased intensity sufficient to destroy thecalculus. The generating circuits 127a to 127l are connected to timingcircuits 128 a and 128l, respectively, which control the timing of theshock wave.

The piezoelectric elements 126a to 126l are disposed along an arc, andan ultrasonic probe 110B of mechanical scan type is disposed between thecentral piezoelectric elements, namely, 126f, 126g, for the purpose ofobservation. The probe 110B is connected to a transmit/receive circuit111A. When a transmission signal is delivered from the circuit 111A tothe probe 110B, the latter produces an ultrasonic beam which is directedtoward a coeloma, and the beam which is reflected by the calculus 103Dlocated within an affected part is received by the probe 110B and thenfed to the receive circuit 111A, thus allowing the location of thecalculus 103D to be detected. The reception output from the circuit 111Ais supplied to an A/D converter 113.

Selected signals processed by the circuit 111A are fed to CPU 121, andthe memory cycle takes place in substantially the same manner asdescribed above in connection with the eighth embodiment shown in FIG.18, and therefore will not be specifically described, except to notethat corresponding parts are designated by like reference numerals. Anaddress bus 122 and a data bus 120 are connected to the timing circuits128a to 128l.

In operation, the probe (with the piezoelectric elements 126a to 126l)is brought into contact with the body 101B through the interposed waterbag 104B. The probe 110B performs a sector scan, thus deriving an echosignal from the body 101B, the kidney 102B and the calculus 103D. Theecho signal is processed by the transmit/receive circuit 111A, and fedthrough a frame memory 114 to derive a signal representing a tomographicimage of an object being examined. The tomographic image is displayed onCRT display 112. While observing the display 112, an operator adjuststhe location of the water bag and the probe, so that the focal point ofthe quadratic surface along which the piezoelectric elements 126a to126l are disposed coincides with the calculus 103D. Such adjustmenttakes place by a system disclosed in U.S. Pat. No. 4,617,931.

Data read from the frame memory 114 is fed through a read buffer circuit115 to a comparator 116, which is operative to extract the addresses ofonly those signals having levels greater than a given value, and theseaddresses are fed to the data bus 120 together with data from the readaddress generator 118. In this manner, CPU 121 stores the addresses ofonly those signals having a high brightness. The extracted addressesrepresent a digital value indicative of the location of the calculus.The timing with which the piezoelectric elements 126a to 126l are drivenare adjusted to focus the ultrasonic beam produced by these elementsupon the focus thus determined.

FIG. 22 graphically illustrates the steps of bringing and maintainingthe focal point of an ultrasonic beam emitted by the piezoelectricelements 126a to 126l into and in coincidence with the location P_(I) orP_(II) of the calculus 103D. An ultrasonic wave transmitting surfacewith a two-dimensional spherical shell is developed in front of thepiezoelectric elements 126a to 126l as indicated in dotted lines in FIG.22. Assuming that the focal point of the ultrasonic wave having the wavesurface W_(I) coincides with the location of P_(I) of the calculus, ifthe calculus 103D moves from the location P_(I) to P_(II) (as a resultof breathing, for example) the focal point must be rapidly moved fromP_(I) to P_(II), thus displacing the transmitting wave surface W_(I) toanother transmitting surface W_(II). In order to achieve the wavesurface W_(II), the timing of a signal applied to the piezoelectricelement 126a is chosen to be earlier than the timing of a signal appliedto the piezoelectric element 126l by a time interval T. The same is truewith respect to the remaining 126b to 126k.

Signals which drive the piezoelectric elements 126a to 126l are derivedby the shock wave generating circuits 127a to 127l, in a mannerillustrated in FIG. 23. The relative timing between the signals appliedto the individual piezoelectric elements is determined by the timingcircuits 128a to 128l by signals delivered from CPU 121 over the databus 120. In this manner, a time difference T between the wave surfacesW_(I) and W_(II) is achieved.

FIG. 24 is a flowchart of a timing control. Specifically, the locationof a calculus is compared against a focal point predicted from theprevailing timing. If a coincidence therebetween is not reached, thetiming is modified, while the present timing is used to develop pulsesif the coincidence is maintained. In this manner, the timing of thedriving of the individual piezoelectric elements which are distributedin three dimensions along a spherical surface in a mosaic pattern iscontrolled to achieve a focal point which automatically tracks thecalculus.

In this manner, in accordance with this embodiment, data representing alocation of an affected area is derived by means which continuouslyoperate to detect the location of such area. Such data is utilized todrive focussing means to bring the focal point into coincidence with theaffected area, the focusing means controls the timing with which theindividual piezoelectric elements are driven. In this manner, focussingis accomplished without any time lag in the presence of a movement ofthe affected area, thus improving the efficiency with which a calculusis fractured. Furthermore, normal tissues are not damaged.

FIG. 25 is an illustration of part of a twelfth embodiment of theinvention which is designed for thermal therapy of a tumor. In thisembodiment, the arrangement is generally similar to the eleventhembodiment except that a number of piezoelectric elements 132 aredisposed in a matrix forming a plane, thus constituting together a group131 thereof. An ultrasonic probe 110B is disposed at the center of thematrix to detect the location of a tumor 130, and the group ofpiezoelectric elements 131 emits an ultrasonic beam which is directedtoward the tumor 130 for thermal therapy thereof. Where the tumor 130has an extensive area, a scan of the ultrasonic beam may be utilized.

FIGS. 26A to 26C illustrate a thirteenth embodiment of the inventionwhich utilizes an acoustical prism to rapidly change the focal point ofthe ultrasonic shock wave. Referring to FIG. 26A, an acoustical prism147 (with a pair of oppositely located lid plates 141, 142 of equal sizeand configuration and connected together by bellows 143) is containedwithin a water bag 104C. The internal space defined between the lidplates is filled with liquid having an acoustical refraction indexgreater than that of a liquid contained within the water bag 104C andsupplied from a liquid tank 146. As illustrated in FIGS. 26A to 26C,four pistons 140a to 140d are located at an equal interval around theacoustical prism 147 to permit the spacing between the lid plates to bechanged at will. Specifically, each of the pistons 140a to 140d includesa cylinder chamber which is connected through an associated pump 144a to144d (144b to 144d not being shown) to an oil tank 125, as illustratedin FIG. 26A. The pumps 144a to 144d are controlled by a processor, notshown. An ultrasonic probe 110C for detecting the location of a calculusis disposed intermediate the acoustic prism 147 and the calculus.

In operation, movement of the calculus from location P_(I) to a locationP_(II) is detected by the ultrasonic probe 110C, and an address signalcorresponding to the location P_(II) is fed to the processor mentionedabove, which then responds thereto by calculating the orientation inwhich the ultrasonic beam is to be focussed, delivering the controlsignals fed to the pumps 144a to 144d. By activating the pistons 140a to140d in a corresponding manner, the configuration of the acoustic prism147 may be modified so that the ultrasonic beam is focused upon thelocation P_(II) of the calculus. Thus, referring to FIG. 26A, when thelid plate 141 of the acoustical prism 147 is located as indicated by thesolid line, the ultrasonic wave emitted by the piezoelectric elements126a to 126l is focused upon the location P_(I), but as the piston 140aprojects while the piston 140c retracts into its cylinder to displacethe lid plate 141 of the acoustical prism 147 to the dotted lineposition to thereby change the acoustic impedance, the focussingdirection shifts downward, whereby the ultrasonic wave is focused on thelocation P_(II). In this manner, the focal point of the ultrasonic wavemay be changed rapidly, enabling a quick, automatic tracking operation.A change in the volume of the acoustical prism 147 takes place byincreasing or decreasing the liquid quantity in the liquid tank 146.

FIG. 27 is a schematic illustration of an apparatus according to afourteenth embodiment of the invention, which is designed to cover anextended area to facilitate determining the location of a calculusbefore it is treated. There is shown the physical body 151 of a patentwhich contains a calculus 152 therein. A pair of electronic scan typeultrasonic probes 153, 154 are used to obtain a tomographic image overan area encompassed by a pair of dotted lines 165, 166. The probe 153 isdisposed for angular movement as by a probe driver 158 which may includea stepping motor, for example. On the other hand, the probe 154 isdisposed for angular movement as well as for movement in threedimensions by a probe driver 158 (which may include a stepping motor orX-Y-Z stage). The probe 153 is located at the center of an ultrasonicwave generator 155 while the probe 154 is located at a lateral positionadjacent thereto. The generator 155 includes a number of ultrasonicvibrators in an array along a spherical shell to produce an ultrasonicwave of an increased intensity at the focus F of the shell in responseto a drive from a drive circuit 156. A water bag (not shown) formed of asoft resin material and filled with an ultrasonic wave transmittingmedium such as water is interposed between the generator 155 and thepatient 151.

An ultrasonic measuring apparatus 159 delivers a transmit pulse to theprobes 153 and 154 through a rotary transformer 157, and a receivedpulse from the probes 153, 154 is fed through the transformer 157 backto the observation apparatus 159 so as to be displayed as a B-modeimage. The rotary transformer 157 is conventional and permits anelectrical signal to be transmitted to a rotating member withoutelectrical contact. Image information from the measuring apparatus 159is fed to an image processor 160 where the coordinates of the center ofgravity of the calculus are calculated. A location detector 161 respondsto a difference between the coordinates of the center of gravity and thecoordinates of the focus F of the generator 155, by causing a positioncontroller 162 to drive a shifting unit 163 to bring both points intocoincidence.

In operation, when a tomographic image acquired by the probe 153 failsto locate a calculus, the probe 154 is initially rotated about itscenter axis 168 while causing it to revolve about the center axis 169 ofthe generator 155, thus causing it to scan across an extensive area inX, Y and Z directions to search for the calculus 152 within the patient151. If the presence of a calculus is recognized in a certaintomographic image, such position information is utilized to cause theposition controller 162 to drive the shifting unit 163 to move thelocation of the calculus 152 into a measurable range 165 having thefocus F of the generator 155 on its center axis 169. After suchmovement, the location of the calculus 152 is automatically tracked onthe basis of a tomographic image from the probe 153, covering themeasurable range 165 for performing a fracturing operation.

Specifically, an ultrasonic echo signal from the probe 153 is fedthrough the rotary transformer 157 to the measuring apparatus 159 wherea B-mode image is obtained. This information is then fed to the imageprocessor 160 where digitization and calculation of an area are made toextract the position of the center of gravity of the calculus 152 whichis then delivered to the location detector 161. The location detector161 detects a difference between the location of the center of gravityand the location of the focus F, and the difference signal is output tothe position controller 162. The position controller 162 drives theshifting unit 163 so that both points are brought into coincidence witheach other. The described operation is repeated to focus continuously.Thus, in this embodiment, the searching probe 154 significantly extendsthe measurable range, facilitating the coarse location of the calculusto be determined. The automatic tracking of the calculus greatlyimproves the efficiency of the fracturing operation.

In this embodiment, it is assumed that the center of gravity of acalculus, as determined by the processing of echo signals, representsthe actual location of the calculus during the automatic tracking of thecalculus. However, a fracturing operation may also be contemplated inwhich the size of a calculus is determined on the basis of the area ofecho-throughs 150A, 150B (see FIG. 21), and the fracturing operation iscontinued until this area reduces below a given value. It is alsopossible to detect the size of the calculus by a treatment which removesthe respective echo-throughs.

FIG. 28 is a schematic illustration of an apparatus according to afifteenth embodiment of the invention, which is generally similar to theapparatus illustrated in FIG. 27 except that a searching probe 154 hasan oscillatable axis 168 directed toward the center axis 169 on whichthe focus F of the ultrasonic wave generator 155 is located. Theoscillation of the probe 154 enables it to oscillate in a directionindicated by an arrow in following relationship with the calculus 152during the time the generator 155 is moved so as to bring the focus Fthereof into coincidence with the calculus after the calculus 152 hasbeen found on the axis 168A, thus maintaining its axis 168A in alignmentwith the calculus 152. After the generator has been focussed upon thecalculus 152, the calculus 152 is automatically tracked on the basis ofa tomographic image acquired by the probe 154. This embodiment has asimplified, smaller construction because it does not include thecentrally located probe 153. FIG. 29 illustrates echo-throughs 150A,150B caused by the calculus 152 in a tomographic image acquired by theprobes 153, 154.

FIG. 30 illustrates an ultrasonic therapeutical apparatus according to asixteenth embodiment of the invention which is designed to provide athree-dimensional scan by an ultrasonic probe to acquire a plurality oftwo-dimensional tomographic images, representing sections of thephysical body of a patient, which are then processed in real time tolocate the calculus, positional information of which is utilized forfocussing an ultrasonic wave.

In FIG. 30, an array 177 of ultrasonic vibrators or piezoelectricelements 183 disposed along a spherical surface in a mosaic pattern isdriven by a drive circuit 180 to develop an ultrasonic wave of anincreased intensity. The wave is focussed upon a focus F of the array177. An ultrasonic probe 172 of electronic sector scan type derives atomographic image of a sector-shaped area encompassed by broken lines.

The space between the patient 171 and the probe 172 is filled with amedium such as water to prevent attenuation of the ultrasonic wave.Alternatively, a bag filled with water, not shown, may be in closecontact with the patient 171 while covering the array 177. The probe 172is driven in an angular increment of 45°, for example, by an ultrasonicscanner 173 which may include a stepping motor, and at each angularposition, an ultrasonic measuring apparatus 174 delivers an ultrasonictransmit pulse fed through a rotary transformer 184. An echo signal fromthe probe 172 is fed back to the measuring apparatus 174 through thetransformer 184 to display a B-mode image. A video signal from theapparatus 174 is fed to an image processor 175, which cooperates with alocation detector 176 to obtain information representing the location ofa calculus 181, with such information being fed to a position controller179. Information representing the angle of rotation of the steppingmotor is supplied from the scanner 173 to the position controller 179,which then activates the array shifting unit 178 on the basis of suchinformation.

In operation, the probe scanner 173 rotates the probe 172 throughangular increments to provide a B-mode image at each angular positionwhich may correspond to an angular increment of 45°, for example, asillustrated in FIG. 31. By extracting areas of the image which exceed agiven threshold in strength, four images P1 to P4 are obtained asindicated in FIG. 32. The combination of the image processor 175 and thelocation detector 176 operate upon each of these images P1 to P4according to an algorithm indicated in FIG. 33. In this manner,information representing the B-mode image from the measuring apparatus174 is acquired and stored in the image processor 175. Digitization maybe performed to extract signal portions which exceed a given threshold,thereby facilitating the extraction of an echo which exhibits a greaterstrength than the remaining tissues. The echo area over such extractedportions of the calculus 181 is then calculated. One of the four imagesP1 to P4 which exhibits a greater area extracted for the calculus, whichis the image P2 in the present example, is then determined. Acorresponding angle of the scanner 173 (which is equal to 45° in thisexample) is determined. The location of the center of gravity G of thecalculus represented by the echo in this plane is then determined (seeFIG. 34), thus delivering the coordinates of the center of gravity G.

The location detector 176 then determines deviations Δx and Δy (see FIG.34) of the center of gravity G from the focus F of the array 177 as wellas the corresponding angle θ (see FIG. 34) of the probe scanner 173,delivering such information to the position controller 179. In responseto information representing Δx, Δy and θ, the position controller 179drives the array shifting unit 178 (which may include an X-Y Z stage,for example) thus bringing the focal point F of the array 177 intocoincidence with the calculus 181 (see FIG. 30). Under this conditionthe drive circuit 180 drives the array 177, causing the latter to emitan ultrasonic wave of an increased intensity concentrated upon thecalculus situated at the focus F, thus fracturing it.

In the described embodiment, the B-mode image is acquired for eachrotation of the probe through an angular increment of 45°, but theangular increment is not limited to this value. A smaller angularincrement may be chosen to achieve a positional adjustment with a higheraccuracy. For example, by driving the probe scan 173 at a rate of tworevolutions per second and acquiring the image at an angular increment θof 5°, thirty-eight B-mode images over an angular range of 360° may beprocessed within a time interval of 0.5 second, which is sufficient fortracking movement of the calculus for practical purposes. In thismanner, the focus F of the ultrasonic wave is maintained at the centerof gravity of the calculus which is represented by the echo, thusassuring maximum fracturing efficiency whenever the drive circuit 180 isenergized.

FIG. 35 illustrates a mode image illustrating another use of thetherapeutical apparatus illustrated in FIG. 30. It is assumed in theembodiment of FIG. 30 that the center of gravity of the echorepresenting a calculus coincides with the actual center of gravity ofthe calculus. However, with a calculus which exhibits an increasedhardness, the nature of the ultrasonic wave may cause an echo 185 of anincreased magnitude to be developed at the boundary of the calculus 181located toward the probe 172 while failing to provide any echo for theremainder. In such a situation, a calculated location of the center ofgravity of the echo may depart from the actual center of gravity of thecalculus 181. To accommodate for this problem, the actual location ofthe calculus 181 may be inferred from a point nearest the probe 172 orfrom a configuration of the echo.

The probe 172 described above is an electronic sector type probe.However, a convex, linear or mechanical scan type probe may be usedinstead. Also, while the preferred embodiments have been described assystems for fracturing a calculus, the invention is also applicable todissolution of thrombus, release of a progressively releasable agent(wherein an ultrasonic wave is externally irradiated upon a mass ofmaterial in which a medicine is impregnated to cause a progressiverelease of the latter), hypothermia or the like.

FIG. 36 illustrates means for displaying an image obtained from anapparatus constructed according to a seventeenth embodiment of theinvention and which is utilized to position a calculus into coincidencewith a focal point of a fracturing shock wave. In this Figure, anultrasonic vibrator 191 is driven by a transmit/receive circuit 192 todetect the spatial location of a calculus situated within the physicalbody of a patient. An ultrasonic echo signal received by thetransmit/receive circuit 192 is fed through an A/D converter 193, whereanalog-to-digital conversion is made, to a first memory 194 which storesultrasonic image data.

On the other hand, data representing the distribution of intensity of ashock wave from a shock wave generator, not shown, is previouslycalculated and stored in a second memory 196 which also defines an imagememory. Both memories 194, 196 are controlled by a control circuit 195,which effects inputting image data from the respective memories into animage processor 197 where both data are synthesized. Specifically, basedon the data representing the distribution of intensity of a shock wavesupplied from the second memory 196, the image processor 197 allocatescolors to the image depending on the intensity of the shock wave, andsuch color distribution signal is superimposed upon data representing anultrasonic tomographic image supplied from the first memory 194. Thesuperimposed signal is converted into standard television form by astandard television signal converter 198 before it is fed to a colordisplay unit 199, which displays the resulting image.

FIG. 37 shows what is displayed on the screen of the color display unit199. An ultrasonic tomographic image 200 and an image 201 representingthe distribution of intensity of a shock wave are both superimposed uponeach other on the screen. Since the image 201 is displayed in colors insuperposition with the tomographic image 200 it is a simple matter todetermine the location within the living body where the shock wave isapplied and what the intensity of the shock wave is. This facilitatesand assures that the calculus B is positioned at the point of maximumintensity of the shock wave. It is also easily determinable whetherorgans such as a lung, intestines or bones (which are sensitive to ashock wave) are close enough to risk damage, thus enabling any damage tothese organs to be prevented.

In this embodiment, ultrasonic vibrators can be located at positionsdisplaced 90° from each other so that the resulting tomographic imagesmay be superimposed upon the distribution of intensity of the respectiveshock waves on the screen of the color display unit 199.

FIG. 38 illustrates another image display means in accordance with theinvention. In this embodiment, coincidence of a calculus 202 with thepoint of maximum intensity of the shock wave is indicated by a change inthe display within an image processor 197. FIG. 38 only illustrates theinternal construction of the image processor 197, with the remainingconstruction being similar to that of FIG. 36. Specifically, tomographicdata stored in a first memory 194 and data representing the distributionof intensity of a shock wave which is previously calculated and storedin a second memory 196 are fed to the image processor 197. Datarepresenting the distribution of intensity of the shock wave is fed to apeak detector 203 where data having a maximum intensity is detected. Anaddress corresponding to such data is fed to a control circuit 195 andthen to a gate 204. Data representing a tomographic image supplied fromthe first memory 194 passes through the gate and an output of the datais fed to a comparator 205. Since the acoustical impedance of a calculusgreatly deviates from the acoustical impedance of a living body, thecalculus appears as an increased magnitude echo signal. A threshold ofthe comparator 105 is chosen whereby only the calculus is detected. Whena signal exceeding the threshold or a picture signal of the calculus issupplied to the comparator 205, the color allocated to the tomographicimage of the calculus is changed. An image processor 206 combines asignal representing the tomographic image from the first memory 194, anoutput from the comparator 205 and data representing the distribution ofintensity of the shock wave (supplied from the second memory 196)together, and the combined signal is fed to a standard television signalconverter 198 to permit it to be displayed on a color display unit 199.In this embodiment, when the calculus is positioned at a point ofmaximum intensity of the shock wave, a change in the color of thecalculus occurs. This assures reliable positioning of the calculus.

FIG. 39 illustrates an apparatus according to an eighteenth embodimentof the invention, specifically, an ultrasonic probe and a shock wavegenerator of an ultrasonic observation apparatus as well as a water bagin longitudinal section. FIG. 40 illustrates the generator and the waterbag in plan view, and FIG. 41 is an enlarged longitudinal section of atop portion of FIG. 39. In this embodiment, a high tension dischargetype shock wave generator is used to generate a shock wave to fracture acalculus. Specifically, the shock wave generator 211 includes aparaboloidal metal plate 212, high tension discharge electrodes 213 anda high tension source 214. A water bag 215 formed by a thin film isconnected to the metal plate through bellows 216 which are connected tothe upper edge of the metal plate 212, thus covering the top surface ofthe metal plate. An ultrasonic probe 217 with an array of ultrasonicvibrators is secured to the upper surface of the water bag 215 with acarrier member 218 (see FIG. 41) interposed therebetween. The probe 217is connected through a lead wire 219 to a measuring apparatus, notshown. The discharge electrodes 213 are spaced apart, with the gaptherebetween being centered about one of the foci, Fa, of theparaboloidal plate 212, and the shock wave is efficiently focussed uponthe other focus Fb where a calculus or the like may be located.

The water bag 215 is made of GOATEX (trademark) which is permeable to agas such as air, but which is impermeable to a liquid such as water. Thebag 215 is internally filled with a shock wave transmitting medium suchas water, and is deformable. The bag also includes means for injecting aliquid and means for controlling the pressure thereof. The probe 217 maybe formed of a thin piezoelectric film of PVDV (polyvinylidenefluoride). It is supplied to the surface of the water bag 215 to effecta linear or a sector scan.

In operation, the surface of the water bag 215 is applied to the surfaceof the physical body of a patient in a region opposite to an affectedarea, and the probe 217 is utilized to scan the affected area todetermine the location of a calculus or the like. Subsequently, theshock wave generator 211 is operated to bring the focus Fb of theparaboloidal plate 212 into coincidence with the calculus. A hightension discharge then takes place between the electrodes 213.Thereupon, a resulting shock wave is focussed upon the calculus locatedat the focus Fb, whereby the calculus is efficiently fractured.

Since the measuring unit is held in close contact with the patient, thedistance to the affected area can be minimized to assure accuratemeasurement and to reliably detect the calculus. Where a piezoelectricfilm (such as the film mentioned above) is used, a high ultrasonicfrequency can be used. This improves resolution relative to a probe witha conventional ceramic piezoelectric vibrator. This permits precisedetection. The carrier member 218 (which supports the probe 217) may besimply placed on the surface of the water bag 215. Such a simplearrangement reduces cost.

In the described embodiment, the probe 217 has a linear array, but otherarrangements of ultrasonic vibrators may also be used as illustrated inFIGS. 42 and 43. Specifically, a piezoelectric film type ultrasonicprobe 217A with piezoelectric elements disposed in concentric circlesand a plurality of tomographic images may be obtained by scanning indifferent directions which represent an equal division of acircumference such as a-a, b-b, c-c and d-d directions. In this manner,the location of the calculus can be easily and accurately determined.The high tension discharge type ultrasonic generator in the describedembodiment may be replaced by an ultrasonic shock wave generator withpiezoelectric elements.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

We claim:
 1. An extracorporeal therapeutic apparatus, comprising:alocating system for locating a calculus within a patient by utilizingX-rays or ultrasonic waves; shock wave generating means for generating ashock wave for therapeutically treating said calculus; focusing meansfor focusing said shock wave upon said calculus; positioning means forpositioning said locating system and said shock wave generating means atdesired positions with respect to said patient; a shock wave generatorincluding a plurality of ultrasonic vibrators located on a sphericalsurface in a mosaic pattern; an ultrasonic probe for scanning anddetecting said calculus; means for determining the distance to saidcalculus and for calculating the desired focal length of said shockwave; and selecting means for selecting some of said ultrasonicvibrators to be driven as a function of said desired focal length. 2.The apparatus of claim 1, wherein said ultrasonic probe is a mechanicalscan type ultrasonic probe and is centrally located within said shockwave generator.
 3. The apparatus of claim 1, wherein said locatingsystem feds a signal representing a tomographic image obtained byprocessing an echo signal resulting from a scan by said ultrasonic probeto a CRT monitor and a memory to write data representing saidtomographic image into said memory.
 4. The apparatus of claim 3, whereinsaid memory is connected to a multiplexer for switching between outputsfrom a write address generator and a read address generator, and whereinsaid data is fed through a read buffer and a comparator to a CPU.
 5. Theapparatus of claim 4, wherein said comparator includes means fordistinguishing tomographic data from said patient which exceeds athreshold value and for feeding an address of said data which exceedssaid threshold value to said CPU.
 6. The apparatus of claim 4, whereinsaid CPU includes means for calculating the distance to said target onthe basis of data from said comparator and said read address generator.7. The apparatus of claim 4, further comprising drive circuits connectedto said CPU for individually driving said vibrators.